JPH05154899A - Preform heating device - Google Patents

Abstract

PURPOSE:To obtain a preform heating device preventing a heating body from being adversely affected in temperature control by no-lood heating and being improved in thermal efficiency and facilitated in maintenance or the like by forcibly cooling a heat release part of the heating body. CONSTITUTION:A preform heating device is provided with a plurality of mandrels 14 movably provided in a heating furnace and heating bodies 3 each made of a heat pipe and vertically mounted on each of the mandrels 14. In this heating device, preforms inserted over the upper ends of the heating bodies 3 are heated from the external by a heater and from the internal by the heating bodies 3. A heating body cooler 30 is provided on a preform travel path between a preform supply table and a carry table for carrying the preforms to a molding machine.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a preform heating device for biaxial stretch blow molding.

[0002]

2. Description of the Related Art In a biaxial stretch blow molding method for a synthetic resin bottle, a bottomed cylindrical preform (primary molded product) 1 as shown in FIG. 9 is heated to a predetermined temperature prior to stretch blow molding. , The stretching effect must be obtained.

At present, in a high-speed type biaxial stretch blow molding machine, in order to perform molding at high speed, the preform 1 is externally heated by an infrared heater 2 as shown in FIG. And the preform 1 is also heated from the inside by utilizing the heat radiation.

This heating element 3 is a so-called heat pipe, and as shown in FIG. 10, a working liquid 5 is enclosed inside a vacuum metal sealing tube 4, and this heating element 3a is provided in the lower heating section 3a. The working fluid 5 is heated and evaporated, and the heat is radiated by condensing the vapor of the working fluid 5 in the upper heat radiation portion 3b. As a heating means for the heating element 3, for example, a high frequency induction heating coil 17 arranged around the lower part of the heating element 3 is used to directly heat the heating element 3.

[0005]

In the blow molding machine described above, since the preform 1 is not supplied during the preliminary operation, that is, before the molding conditions of the infrared heater 2 are satisfied before the molding is started, the inside of the heating furnace is not supplied. Is in a so-called idling state in which the heating element 3 revolves while being exposed. Since the preform 1 is not externally attached to the heating element 3 during this idle operation, the infrared heater 2 causes the heat radiating portion 3b of the heating element 3 to move.
Direct heating of the empty space occurs. Also, during molding, when the trouble of the preform supply table or the shortage of the preform 1 occurs, the void similarly occurs.

In this empty state, the heating element heat radiation portion 3b
Since the heating energy from the infrared heater 2 that heats the outside of the preform 1 is much larger than the energy radiated from the high-frequency induction heating, the target temperature condition of the heat radiating unit 3b is exceeded. There is a problem in that it is not possible to accurately grasp how many times the heat radiating portion 3b actually becomes due to the energy supplied from the means, and it becomes difficult to control the temperature thereof, and it becomes impossible to achieve accurate heating control of the preform 1. It was

Further, due to the characteristics of the heating element 3, when the heat radiating portion 3b is rapidly heated in the air or the like, the heating efficiency of the high frequency induction heating means deteriorates, and a large amount of energy is required to exert a desired heating capacity. However, there is a problem in that the heating balance between the infrared heater 2 and the preform 1 cannot be properly maintained in some cases.

Further, in the case of replacement or maintenance of the heating element 3, it is necessary to lower the temperature of the heat radiating portion 3b to a certain value or less, but the temperature of the heat radiating portion 3b naturally decreases to a certain value or less. If it is achieved by heat radiation, it takes too much time, and there is a problem in that it is not possible to obtain an appropriate timing for replacement of the heating body 3 or maintenance.

Therefore, the present invention was devised to solve the above-mentioned problems in the prior art. The technical problem is to prevent the heat radiating portion of the heating body from overheating. It is an object of the present invention to provide a preform heating device that prevents adverse effects on control, improves heating efficiency, and facilitates maintenance and the like.

[0010]

Means for Solving the Problems The means of the present invention for solving the above technical problems comprises a plurality of mandrels rotatably movable in a heating furnace, and a heat pipe vertically attached to each mandrel. A heating unit, and a heating unit for heating a preform externally fitted to the upper end of the heating unit with a heater from the outside and a heating unit from the inside, and a feeding unit for the preform and a transfer unit for sending the preform to a molding device. The heating body cooling device is installed between and.

[0011]

The heating element cooling device is prevented from being overheated by the heater by operating the heating element cooling device when necessary during the preliminary operation or maintenance of the heating element, and the temperature control of the heating element is accurately performed. In addition to being able to perform maintenance, it is possible to perform maintenance and the like promptly.

[0012]

EXAMPLE FIG. 5 is a plan view of a biaxial stretch blow molding machine, in which 10 is a preform heating apparatus, 11 is a molding apparatus,
30 is a heating body cooling device. As shown in FIGS. 4 to 6, the preform heating device 10 is provided with a heating furnace 12 on the peripheral edge of the rotary table 13, and the outer peripheral edge of the rotary table 13 is circumferentially equidistant. Mandrel 1
4 are rotatably arranged, and a heating element 3 (FIG. 10) is vertically attached to each mandrel 14. This heating element 3 uses a so-called heat pipe as described above.

Reference numeral 16 is a fixed gear which meshes with a gear 15 provided on each mandrel 14. Therefore, when each mandrel 14 revolves with the rotation of the rotary table 13, it is rotated by the fixed gear 16.

Infrared heaters 2 for heating the preform 1 from the outside are provided on the inner and outer peripheral sides of the heating furnace 12. On the other hand, on the inner peripheral side and the outer peripheral side of the lower part of each heating element 3,
The high frequency induction heating coil 17 is arranged in an arc shape along the movement path of the heating body 3. This induction heating coil 1
7 is a stack of a plurality of hollow copper pipes, the starting end side of which is connected to a high-frequency induction heating and oscillating device 18, and the continuous bending portion 19 at the tip end of the heating element 3 is shown in FIG. It is bent downward so as not to hinder movement.

In FIG. 5, 20 is a preform supply table, 21 is a transfer table for sending the heat-treated preform 1 to the molding apparatus 11, 22 is a mold station table, and 23 is a molded product ( Bottle)
Is a discharge table of.

An infrared radiation thermometer 24 is installed between the preform supply table 20 and the transfer table 21 to constantly measure the temperature of the heat radiating portion 3b above the heating body 3. This thermometer 24 is an automatic temperature control device 25.
This automatic temperature control device 25 is connected to
Is connected to the control device 26 and the high frequency induction heating and oscillating device 18.

Infrared radiation thermometer 24 and transfer table 21
A heating body cooling device 30 is installed on the moving path of the heating body 3 between and. As shown in FIGS. 1 to 3, the cooling device 30 has a substantially gate-shaped cross section so as to cover the heat radiating portion 3b of the heating body 3 passing therethrough from above while allowing the heating body 3 to pass freely. The fixed gear 1 is formed by the pair of columns 31.
It is fixed at 6. Cooling gas outlets 32 are provided at regular intervals on the lower surface of the top plate of the cooling device 30, and a gas of a predetermined temperature is blown out from the outlets 32 so that the heat radiating portion 3b of the heating element 3 passing therethrough is provided. Cooling.

Next, the operation of the preform heating device 10 will be described. A predetermined high-frequency current is sent from the high-frequency induction heating oscillator 18 to the induction heating coil 17, whereby the heating body 3 directly generates heat, and the heat radiating portion 3b above the heating body 3 is generated.
It radiates heat from.

The preform 1 supplied from the supply table 20 is externally inserted on the upper part of the heating body 3 of the mandrel 14 as shown in FIGS. 4, 6 and 8 and rotates in the heating furnace 12 together with the rotary table 13. While revolving around. During this movement, the preform 1 is heated by the infrared heater 2 on the outside and the heating body 3 on the inside to a temperature at which the effect of the stretch blow molding is obtained, and then sent to the mold of the molding apparatus 11 by the transfer table 21. ..

When necessary, for example, during a preliminary operation of the preform heating device 10 before the start of molding, the heating body cooling device 30 is operated to cool the heat radiating portion 3b of the heating body 3 to a predetermined temperature by the cooling gas. In that case, for example, use normal temperature air,
It is desirable to cool the heat radiating portion 3b of the heating element 3 at 200 ° C. or higher to around 150 ° C. The cooling capacity of the cooling device 30 can be adjusted by the temperature of the gas used, the amount of gas blown out, or the like.

The infrared radiation thermometer 24 measures the temperature of the radiation portion 3b of each heating element 3 and sends the measured data to the automatic temperature control device 25. In this control device 25, a comparison calculation is performed to maintain the temperature of the heating body heat radiating portion 3b which is input and set in advance from the outside, and the result is sent to the high frequency induction heating oscillation device 18 as an output signal to the induction heating coil 17. It constantly controls the current to flow.

By this feedback control, it is possible to instantly follow the temperature change of the heating body heat radiating section 3b due to the change of the environmental temperature in the factory, etc. Also, when starting the supply of preform or changing the molding conditions, the heating body heat radiating section is performed. It is possible to confirm whether or not the temperature of 3b satisfies the target condition.

[0023]

According to the present invention, the heater is prevented from being overheated by the heater by operating the heater cooling device when necessary during pre-operation, maintenance, etc. The temperature control can be accurately performed, the heating efficiency can be improved, and the maintenance and the like can be performed quickly.

[Brief description of drawings]

FIG. 1 is a front view of a heating body cooling device according to an embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a side view of the same.

FIG. 4 is a sectional view taken along line CC in FIG.

FIG. 5 is a plan view of the same biaxial stretch blow molding machine.

FIG. 6 is a sectional view taken along line AA of FIG.

FIG. 7 is a view taken in the direction of arrow B in FIG.

FIG. 8 is a principle diagram of the same.

FIG. 9 is a sectional view of the preform.

FIG. 10 is a sectional view of a heating element.

[Explanation of symbols]

1; Preform 2; Infrared heater 3; Heating body 3a; Heating part 3b; Heat dissipation part 4; Metal seal tube 5; Working liquid 10; Preform heating device 11; Molding device 12; Heating furnace 13; Rotating table 14; Mandrel 15; Gear 16; Fixed Gear 17; High Frequency Induction Heating Coil 18; High Frequency Induction Heating Oscillator 19; Continuous Bending Section 20; Preform Supply Table 21; Transfer Table 22; Mold Station Table 23; Ejection Table 24; Infrared Radiation Thermometer 25; Automatic temperature control device 26; Control device 30; Heating body cooling device 31; Strut 32; Blowout port

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Claims (2)

[Claims] 1. A heating furnace (2) comprising a plurality of mandrels (14) rotatably movable, and a heating body (3) vertically attached to each of the mandrels (14). ,
A device for heating a preform (1) externally fitted on the upper end of the heating body (3) with an infrared heater (2) from the outside and with the heating body (3) from the inside, which is a device for heating the preform (1). A preform heating device comprising a heating body cooling device (30) provided between a supply part and a transfer part for feeding the preform (1) to a molding device. 2. The heating body cooling device (30), wherein the heat radiating part (3b) of the heating body (3) can be passed through the heating body (3).
The cooling gas blowout port (32) is provided at a constant interval on the lower surface of the top plate which is arranged on the moving path of the heating body (3) and is covered from above and has a substantially gate-shaped cross section. The described foam heating device.